The processing of molds or materials with specific shapes have changed a great deal due to the emergence of wire-arc discharge cutting machinery. The advantages of wire-arc discharge cutting machinery include: highly accurate processing, short processing time, reduction of cost and reduction of design time for the mold. Although discharging processing machinery offers so many advantages, there are still some restrictions thereon, especially in the holder.
Referring to FIGS. 6 and 6A, a conventional holder for discharging processing machinery is shown. The holder 51 utilized in a wire-arc discharge cutting machinery is provided on a frame 5 to hold a processing material 3. A pre-set holding clearance 32 is necessary for the holder 51 to hold the processing material 3 and causes inconvenience while processing. Furthermore, the lower nozzle 41 of the cutting machinery must "face" the processing material in such a manner that the clearance between the processing material 3 and the lower nozzle 41 is in a range not exceeding 0.05 to 0.1 mm. Additionally, there is a dead angle for processing when the lower nozzle 41 and the upper nozzle 4 collide with the holder or frame during the cutting.
In order to eliminate the disadvantages of the above-mentioned holder, some people put the holder seat 7 on the flanges 63 of the fixed seats 6 (See FIG. 7). Movable locking means 61 and tracks 62 provided on each fixed seat 6 and tracks 72 on the holder seat 7 are accommodated to fasten the holder seat 7. The processing material 3 on the flange 73 is fastened to of the holder seat 7 by movable fastener 71. This holder can resolve the inconvenience and limitation of processing the edges of the processing material. However, the clearance between the processing material 3 and the lower nozzle 41 is greater than the overall height of the flange 63 and exceeds 0.1 mm. The cutting rate is largely reduced. Furthermore, the upper nozzle 4 might touch the fastener 51 and cause inconvenience during processing.
As can be seen in FIG. 8, another improved conventional holder is shown. In such holder, adjusting holes 82 and adjusting means 81 are provided on a holder seat 8. The holder seat 8 further includes an inclined surface to which the holder seat 9 is attached. Fastening means 91 are provided to fasten the processing material 3. By inserting the adjusting means 81 into the adjusting holes 82, the position of the processing material 3 can be corrected. This kind of holder is precise in processing. Nevertheless, a skilled operator is required to proceed with the adjustment; furthermore, this kind of holder is expensive. In addition, it does not fit to large materials 3 since the holding strength of the fastening means 91 is limited.